People will be tested for Covid-19 on February 15 at a busy test station in downtown Otara in Auckland, New Zealand. Fiona Goodall / Getty Images

Two of the three new Covid-19 cases that have locked the New Zealand city of Auckland are a variant of the virus first discovered in the UK.

The three local Covid-19 cases announced on Sunday are a mother, father and daughter from the same household in South Auckland, said Director General of Health Dr. Ashley Bloomfield, at a press conference on Sunday. Prime Minister Jacinda Ardern said one of the trios works in a facility that does laundry for airlines.

Auckland Mayor Phil Goff told CNN authorities that individual employment may be “the link” to the virus.

These cases prompted authorities to issue a three-day lockdown for all of Auckland, a city of around 1.5 million and the largest population center in the country, starting at 11:59 p.m. on Sunday

“We are dealing with more transmissible versions, mutations of Covid-19. We want to be very careful. That is why we have chosen this very cautious approach,” said Ardern. “We want people to stay home. So when you’re in Auckland, stay home for the next 72 hours.”

Goff said New Zealand would have found success with the virus if authorities “go strong and early”.

“The government, in consultation with us in Auckland, made the decision to respond in the same way this time,” he said. “After a great weekend of America’s Cup yacht races and the people enjoying the sunshine, beaches, parks, and festivals, we’re suddenly in a 72-hour lockdown.”

Goff said 6,000 to 7,000 people will now be tested for the virus. When these tests are clean again, authorities may be able to lift the new stringent measures.

No new cases were reported on Monday, the country’s health ministry said in a statement